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  • rails Creating a model instance automatically when another is created

    - by bob
    Hello I have a user model and a ratings model. Whenever a new user is created I want to create a new feedback model with it automatically. Each user model has one feedback model and each feedback model has many ratings. My Classes class User < ActiveRecord::Base end class Feedback < ActiveRecord::Base belongs_to :user has_many :ratings end class Rating < ActiveRecord::Base belongs_to :feedback end My database tables -user doesn't have anything special -feedback has user_id. This user_id should be the same as the user that has just been created. For example, user_id of 1 is created, then a feedback model should be created that belongs to user_id of 1. So the user_id column in the feedback database will also be 1. - Rating has a feedback_id and a user_id the user_id in this case is the id of the person who submitted the rating. I am having it assigned through the build command. I believe my process is correct here. The Goal The goal is to have each user have a feedback table that has many ratings from other users. So if someone goes to the feedback page, they will see all the ratings given and by who. Is there a better way to approach this? How do you create a model of feedback with the same id as the user being created right when a new user is created. The idea is that when a user is created a feedback is created associated with that user so people can then go to http://localhost:3000/users/1/feedback/ and submit new ratings. I'm trying to bypass having a user rate another user with just a ratings model because I'm not sure how to do it.

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  • jQuery JSON .each problem

    - by Aran
    I have a JSON object that looks like this. [ { "id" : "23", "event_id" : "0", "sport_title" : null, "event_title" : null, "title" : "Under 1 day!", "content" : "It\\'s all hotting up and battle commences in under one day!", "link" : "" }, { "id" : "20", "event_id" : "0", "sport_title" : null, "event_title" : null, "title" : "Getting Exciting", "content" : "Less than two days till it all kicks off, with cricket....", "link" : "" }] and I am trying to get the details out of this JSON Object and prepend them to a <ul> the code that I am currently trying looks like this and is having problems var writeup_list = writeuplist; $.getJSON('../json/getWriteups.json', function(data) { $.each(data.items, function(i, item) { writeup_list.html(function() { var output; output = '<li><a href="/writeups/index.php#writeup_' + item.id + '">'; if(item.sport_title != null) { output += item.sport_title + ' - '; } output += item.title + '</a></li>'; return output; }); }); }); writeuplist is just the ul object. I am also worried about overriding information that is already in the list or just adding again. Don't want to keep adding the same data. What is a good way to avoid this? I seem to be having a problem in getting the data out of the JSON file I believe it has something to do with the way am trying to access it in the .each function. Can anyone spot where am going wrong?

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  • how to prevent divs from overlapping when using no-wrap across table cells

    - by pedalpete
    I'm trying to create an events calendar which has a somewhat 'gantt' chart like bar representing the times of an event, along with the time listed. I've uploaded a page showing the problem As you can see, the problem is that in the 3rd cell, the event div is being overlapped by the previous event div which goes outside the boundary of the cell. The event from the 2nd cell SHOULD expand beyond the cell border, but what I'm trying to get to happen is that WHEN the event from the 2nd cell expands into the 3rd cell, the event on the 3rd cell starts a new line. I believe the problem exists because of the nowrap on the time, but I want the time and in some cases the bar to cross the cell boundary when the time goes from one day to another. All that works now, but I'm having a problem with events overlapping when an event goes from one day to another. I've tried all sorts of :even cells having a different padding, etc. but all these solutions seem to bring up more problems. Is there a way get the no-wrap to force a new long when it crosses into the next cell? or any other solution to this issue?

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  • How to get XML element/attribute name in SQL Server 2005

    - by OG Dude
    Hi, I have a simple procedure in SQL Server 2005 which takes some XML as input. The element attributes correspond to field names in tables. I'd like to be able to determine <elementName>, <attribNameX> dynamically as to avoid having to hardcode them into the procedure. How can I do this? The XML looks like this: <ROOT> <elementName attribName1 = "xxx" attribName2 = "yyy"/> <elementName attribName1 = "aaa" attribName2 = "bbb"/> ... </ROOT> The stored procedure like this: CREATE PROC dbo.myProc ( @XMLInput varchar(1000) ) AS BEGIN SET NOCOUNT ON DECLARE @XMLDocHandle int EXEC sp_xml_preparedocument @XMLDocHandle OUTPUT, @XMLInput SELECT someTable.someCol FROM dbo.someTable JOIN OPENXML (@XMLDocHandle, '/ROOT/elementName',1) WITH (attrib1Name int, attrib2Name int) AS XMLData ON someTable.attribName1 = XMLData.attribName1 AND someTable.attribName2 = XMLData.attribName2 EXEC sp_xml_removedocument @XMLDocHandle END GO The question has been asked here before but maybe there is a cleaner solution. Additionally, I'd like to pass the tablename as a parameter as well - I read some stuff arguing that this is bad style - so what would be a good solution for having a dynamic tablename? Thanks a lot in advance, /David

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  • Object Oriented Programming in AS3

    - by Jordan
    I'm building a game in as3 that has balls moving and bouncing off the walls. When the user clicks an explosion appears and any ball that hits that explosion explodes too. Any ball that then hits that explosion explodes and so on. My question is what would be the best class structure for the balls. I have a level system to control levels and such and I've already come up with working ways to code the balls. Here's what I've done. My first attempt was to create a class for Movement, Bounce, Explosion and finally Orb. These all extended each other in the order I just named them. I got it working but having Bounce extend Movement and Explosion extend Bounce, it just doesn't seem very object oriented because what if I wanted to add a box class that didn't move, but did explode? I would need a separate class for that explosion. My second attempt was to create Movement, Bounce and Explosion without extending anything. Instead I passed in a reference to the Orb class to each. Then the class stores that reference and does what it needs to do based on events that are dispatched by the Orb such as update, which was broadcast from Orb every enter frame. This would drive the movement and bounce and also the explosion when the time came. This attempt worked as well but it just doesn't seem right. I've also thought about using Interfaces but because they are more of an outline for classes, I feel like code reuse goes out the window as each class would need its own code for a specific task even if that task is exactly the same. I feel as if I'm searching for some form of multiple inheritance for classes that as3 does not support. Can someone explain to me a better way of doing what I'm attempting to do? Am I being to "Object Oriented" by having classed for Movement, Bounce, Explosion and Orb? Are Interfaces the way to go? Any feedback is appreciated!

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  • Entity Framework. Updating EntityCollection using disconnected objects via navigation property.

    - by yougotiger
    I have a question, much liket this unanswered one. I'm trying to work with the entity framework, and having a tough time getting my foreign tables to update. I have something basically like this in the DB: Incident (table): -ID -other fields Responses (table): -FK:Incident.ID -other fields And and entities that match: Incident (entity) -ID -Other fields -Responses (EntityCollection of Responses via navigation property) Each Incident can have 0 or more responses. In my Webpage, I have a form to allow the user to enter all the details of an Incident, including a list of responses. I can add everything to the database when a new Incident is created, however I'm having difficulty with editing the Incident. When the page loads for edit, I populate the form and then store the responses in the viewstate. When the user changes the list of responses (adds one, deletes one or edits one). I store this back into the viewstate. Then when the user clicks the save button, I'd like to save the changes to the Incident and the Responses back to the DB. I cannot figure out how to get the responses from the detached viewstate into the Incident object so that they can be updated together. Currently when the user clicks save, I'm getting the Incident to edit from the db, making changes to the Incident's fields and then saving it back to the DB. However I can't figure out how to have the detached list of responses from the viewstate attach to the Incident. I have tried the following without success: Clearning the Incident.Responses collection and adding the ones from the viewstate back in: Incident.Responses.Clear() for each objResponse in Viewstate("Responses") Incident.Responses.add(objResponse) next Creating an EntityCollection from my list and then assiging that to the Incident.Responses Incident.Responses = EntityCollectionFromViewstateList Iterating through the responses in Incident.Response and assigning the corresponding object from viewstate: for each ObjResponse in Incident.Responses objResponse = objCorrespondingModifedResonseFromViewState Next These all fail, I'd like to be able to merge the changes into the Inicdent object so that when the BLL calls SaveChanges on the changes to both the Incident and Responses will happen at the same time. Any suggestions? I keep finding lots of stuff about assigning foreign keys (singular), but I haven't found a great solution for doing a set of entities assigned to another entity in this manner.

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  • How to get a handle to all JCheckBox objects in order to loop?

    - by EmmyS
    I'm very new to Java and am having some issues looping through JCheckBoxes on a UI. The idea is that I have a bunch of checkboxes (not in a group because more than one can be selected.) When I click a JButton, I want to build a string containing the text from each selected checkbox. The issue I'm having is that our instructor told us that the checkboxes need to be created via a method, which means (see code below) that there isn't a discrete instance name for each checkbox. If there were, I could say something like if(checkBox1.isSelected()) { myString.append(checkBox.getText()); } That would repeat for checkBox2, checkBox3, and so on. But the method provided to us for adding checkboxes to a panel looks like this: public class CheckBoxPanel extends JPanel { private static final long serialVersionUID = 1L; public CheckBoxPanel(String title, String... options) { setBorder(BorderFactory.createTitledBorder(BorderFactory .createEtchedBorder(), title)); setLayout(new BoxLayout(this, BoxLayout.Y_AXIS)); // make one checkbox for each option for (String option : options) { JCheckBox b = new JCheckBox(option); b.setActionCommand(option); add(b); } } } This is called like this: toppingPanel = new CheckBoxPanel("Each Topping $1.50", "Tomato", "Green Pepper", "Black Olives", "Mushrooms", "Extra Cheese", "Pepperoni", "Sausage"); So I now have a panel that contains a border with the title "Each Topping $1.50", and 7 visible checkboxes. What I need to do is get a list of all the selected toppings. We are not supposed to use an ActionListener for each checkbox, but rather get the list when a button is clicked. I'm feeling really clueless here, but I just can't figure out how to get the isSelected property of the checkboxes when the individual checkboxes don't have instance names. Ideally I'd like to somehow add all the checkboxes to an array and loop through the array in the button's action listener to determine which ones are checked, but if I have to check each one individually I will. I just can't figure out how to refer to an individual checkbox when they've been created dynamically.

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  • 'Forward-Compatible' Program Design

    - by Jeffrey Kern
    The majority of my questions I've asked here so far on StackOverflow have been how to implement individual concepts and techniques towards developing a software-based NES clone via the XNA environment. The small samples that I've thrown together on my PC work relatively great and everything. Except I hit a brick wall. How do I merge all of these samples together. Having proof-of-concept is amazing, except when you need it to go beyond just that. I now have samples strewn about that I'm trying to merge, some of them incomplete. And now I'm stuck with the chicken-and-the-egg situation of where I would like to incorporate these samples together, to make sure they work, but I cannot without test data. And I don't have tools to create test data, because they'd need to be based off of the individual pieces that need to be put together. In my mind, I'm having nightmares with circular reference. For my sample data, I am hoping to save it in XML and write a specification - and then make sample data by hand - but I'm too paranoid of manually creating an XML file full of incorrect data and blaming it on my code, or vice-versa. It doesn't help that the end-result of my work is graphic-oriented, which makes it interseting how a graphic on the screen can be visualized in XML Nodes. I guess, my question is this: What design patterns and disciplines exist in the coding world that address this type of concern? I've always relied on brute-force coding and restarting a project with a whole new code base in attempts to further along my goals, but I doubt that would be the best way to do so. Within my college career, the majority of my programming was to work on simple projects that came out of a book, or with a given correct data set and a verifyable result. I don't have that, as my own design documents that I am going by could be terribly wrong.

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  • Injecting Dependencies into Domain Model classes with Nhibernate (ASP.NET MVC + IOC)

    - by Sunday Ironfoot
    I'm building an ASP.NET MVC application that uses a DDD (Domain Driven Design) approach with database access handled by NHibernate. I have domain model class (Administrator) that I want to inject a dependency into via an IOC Container such as Castle Windsor, something like this: public class Administrator { public virtual int Id { get; set; } //.. snip ..// public virtual string HashedPassword { get; protected set; } public void SetPassword(string plainTextPassword) { IHashingService hasher = IocContainer.Resolve<IHashingService>(); this.HashedPassword = hasher.Hash(plainTextPassword); } } I basically want to inject IHashingService for the SetPassword method without calling the IOC Container directly (because this is suppose to be an IOC Anti-pattern). But I'm not sure how to go about doing it. My Administrator object either gets instantiated via new Administrator(); or it gets loaded via NHibernate, so how would I inject the IHashingService into the Administrator class? On second thoughts, am I going about this the right way? I was hoping to avoid having my codebase littered with... currentAdmin.Password = HashUtils.Hash(password, Algorithm.Sha512); ...and instead get the domain model itself to take care of hashing and neatly encapsulate it away. I can envisage another developer accidently choosing the wrong algorithm and having some passwords as Sha512, and some as MD5, some with one salt, and some with a different salt etc. etc. Instead if developers are writing... currentAdmin.SetPassword(password); ...then that would hide those details away and take care of those problems listed above would it not?

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  • ASP.NET MVC WAP, SharePoint Designer and SVN

    - by David Lively
    All, I'm starting a new ASP.NET MVC project which requires some content management capabilities. The people who will be managing the content prefer to use SharePoint Designer (successor to FrontPage) to modify content. I'd like to allow them to keep doing that. The issues are: Since I'd like this to be a WAP, not a website project, how can I allow them to see their changes in action without requiring them to have Visual Studio on their local machines? Can I specify a "default" action for a controller so that given a url like /products/new_view_here Can I let them save pages (views) and see them in the browser without having to go through the check-in/build/deploy process? I'd like their changes to be stored in SVN; SharePoint designer seems to only support Visual SourceSafe (ugh) directly. The ideas I've come up with so far are Write an HTTP handler that implements the FrontPage Server Extensions protocol. This sounds time consuming, but I haven't yet looked at the protocol spec. However, it would allow me to perform whatever operations I want on the server side, including checking files into SVN. Ditch the WAP in favor of a website project. I do not like having the source present on the server, however. Also, will MVC work in a website project? Surely someone has tackled this problem before?

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  • UTF8 charset, diacritical elements, conversion problems - and Zend Framework form escaping

    - by imanc
    Hey, I am writing a webapp in ZF and am having serious issues with UTF8. It's using multi lingual content through Zend Form and it seems that ZF heavily escapes all of these characters and basically just won't show a field if there's diacritical elements 'é' and if I use the HTML entity equivalent e.g. é it gets escaped so that the user will see 'é'. Zend Form allows for having non escaped data, but trying to use this is confusing, and it seems it'd need to be used all over the place. So, I have been told that if the page and the text is in UTF8, no conversion to htmlentities is required. Is this true? And if the last question is true, then how do I convert the source text to UTF8? I am comfortable setting up apache so that it sends a default UTF8 charset heading, and also adding the charset meta tag to the html, but doing this I am still getting messed up encoding. I have also tried opening the translation csv file in TextWrangler on OSX as UTF8, but it has done nothing. Thanks! L

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  • PHP: Profiling code and strict environment ~ Improving my coding

    - by DavidYell
    I would like to update my local working environment to be stricter in an effort to improve my code. I know that my code is okay, but as with most things there is always room for improvement. I use XAMPP on my local machine, for simplicities sake Apache Friends XAMPP (Basic Package) version 1.7.2 So I've updated my php.ini : error_reporting to be E_ALL | E_STRICT to help with the code standard. I've also enabled the XDebug extension zend_extension = "C:\xampp\php\ext\php_xdebug.dll" which seems to be working, having tested some broken code and got the nice standard orange error notice. However, having read this question, http://stackoverflow.com/questions/133686/what-is-the-best-way-to-profile-php-code and enabled the profiler, I cannot seem to create a cachegrind file. Many of the guides that I've looked at seem to think you need to install XDebug in XAMPP which leads me to think they are out of date, as XDebug is bundled with XAMPP these days. So I would appreciate it if anyone can help point me in the right direction with both configuring XDebug to output grind files, and or just a great set of default settings for the XDebug config in XAMPP. Seems there is very little documentation to go on. If people have tips on integrating these tools with Netbeans, that would be awesomesauce. I'm happy to get suggestions on other things that I can do to help tighten up my php code, both syntactically and performance wise Thanks, and apologies for the rambling question(s)! Ninja edit I should menion that I'm using named vhosts as my Apache configuration, which I think is why running XDebug on port 9000 isn't working for me. I guess I'd need to edit my vhost to include port 9000

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  • Mysql Database Question about Large Columns

    - by murat
    Hi, I have a table that has 100.000 rows, and soon it will be doubled. The size of the database is currently 5 gb and most of them goes to one particular column, which is a text column for PDF files. We expect to have 20-30 GB or maybe 50 gb database after couple of month and this system will be used frequently. I have couple of questions regarding with this setup 1-) We are using innodb on every table, including users table etc. Is it better to use myisam on this table, where we store text version of the PDF files? (from memory usage /performance perspective) 2-) We use Sphinx for searching, however the data must be retrieved for highlighting. Highlighting is done via sphinx API but still we need to retrieve 10 rows in order to send it to Sphinx again. This 10 rows may allocate 50 mb memory, which is quite large. So I am planning to split these PDF files into chunks of 5 pages in the database, so these 100.000 rows will be around 3-4 million rows and couple of month later, instead of having 300.000-350.000 rows, we'll have 10 million rows to store text version of these PDF files. However, we will retrieve less pages, so again instead of retrieving 400 pages to send Sphinx for highlighting, we can retrieve 5 pages and it will have a big impact on the performance. Currently, when we search a term and retrieve PDF files that have more than 100 pages, the execution time is 0.3-0.35 seconds, however if we retrieve PDF files that have less than 5 pages, the execution time reduces to 0.06 seconds, and it also uses less memory. Do you think, this is a good trade-off? We will have million of rows instead of having 100k-200k rows but it will save memory and improve the performance. Is it a good approach to solve this problem and do you have any ideas how to overcome this problem? The text version of the data is used only for indexing and highlighting. So, we are very flexible. Thanks,

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  • Foreign/accented characters in sql query

    - by FromCanada
    I'm using Java and Spring's JdbcTemplate class to build an SQL query in Java that queries a Postgres database. However, I'm having trouble executing queries that contain foreign/accented characters. For example the (trimmed) code: JdbcTemplate select = new JdbcTemplate( postgresDatabase ); String query = "SELECT id FROM province WHERE name = 'Ontario';"; Integer id = select.queryForObject( query, Integer.class ); will retrieve the province id, but if instead I did name = 'Québec' then the query fails to return any results (this value is in the database so the problem isn't that it's missing). I believe the source of the problem is that the database I am required to use has the default client encoding set to SQL_ASCII, which according to this prevents automatic character set conversions. (The Java environments encoding is set to 'UTF-8' while I'm told the database uses 'LATIN1' / 'ISO-8859-1') I was able to manually indicate the encoding when the resultSets contained values with foreign characters as a solution to a previous problem with a similar nature. Ex: String provinceName = new String ( resultSet.getBytes( "name" ), "ISO-8859-1" ); But now that the foreign characters are part of the query itself this approach hasn't been successful. (I suppose since the query has to be saved in a String before being executed anyway, breaking it down into bytes and then changing the encoding only muddles the characters further.) Is there a way around this without having to change the properties of the database or reconstruct it? PostScript: I found this function on StackOverflow when making up a title, it didn't seem to work (I might not have used it correctly, but even if it did work it doesn't seem like it could be the best solution.):

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  • Date Picker Control Not Displaying Proper Date (Access 2003)

    - by JPM
    Hi everyone, I just have a quick question. I am maintaining an app for my summer co-op position, and a new requirement came down today where the user requested to have a date control added to a form to mark the date of when an employee is "laid off". This control is enabled/disabled by a toggle button, and has its control source bound to a field that I added in the database. All the functionality has been added and tested, but.... The issue I am having is that the date picker is on a tab control (the 2nd page) and I am having problems trying to get the control to display the date that is stored in the field I created. I know the control is storing any changes made using it, but since the user asked to move the control over to the 2nd tab (it was on the first), it just shows today's date, not the date entered using the control. To make things a little more strange, if I place the control anywhere except the tab control, it seems to be working fine. I've even placed a textbox on the tab and set its control source to the database field, and it displays just fine. What gives? And I have registered the .ocx with Access, and as I mentioned before, the actual database is storing the data. Just not displaying it. Any ideas as to what I am doing wrong?

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  • Swig C++ Lua Pass class by reference

    - by Jeremy
    I don't know why I'm having a hard time with this. All I want to do is this: class foo { public: foo(){} ~foo(){} float a,b; }; class foo2 { public: foo2(){} foo2(const foo &f){*this = f;} ~foo2(){} void operator=(const foo& f){ x = f.a; y = f.b; } float x,y; }; /* Usage(cpp): foo f; foo2 f2(f); //or using the = operator f2 = f; */ The problem I'm having is that, after swigging this code, I can't figure out how to make the lua script play nice. /* Usage(lua) f = example.foo() f2 = example.foo2(f) --error */ The error I get is "Wrong arguments for overloaded function 'new_Foo2'": Possible c/c++ prototypes are: foo2() foo2(foo const &) The same thing happens if I try and use do f2 = f. As I understand it everything is stored as a pointer so I did try adding an additional constructor that took a pointer to foo but to no avail.

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  • [php] Cookies only changing value every two page refreshes?

    - by Gazillion
    Hello, I'm trying to implement some pixel tracking where I will save certain values in a cookie to then forward users to another page. If users purchase a product after being forwarded to the online store by us the store adds an image tag in the page with our php script included. With the values set in the cookie we would like to track conversions. I understand this tracking technique has some limitations (like if a user has cookies turned off or if they do not load images but that's the direction my client wanted to go in). The problem I'm having is that the cookie's behaviour is extremely... random. I've been trying to track their values (with a var_dump so I don't have to wait for a page reload to view the cookie's value) but it seems the value for one field only gets refreshed every two page reloads. setcookie("tracking[cn]", $cn, time()+3600*24*7,'/','mydomain.com'); setcookie("tracking[t]", $t, time()+3600*24*7,'/','mydomain.com'); setcookie("tracking[kid]", $kid, time()+3600*24*7,'/','mydomain.com'); redirectTo($redirect_url); the values of cn, t are fine but for some reason kid is always wrong (having taken the value of the previous kid) Any help would be extremely appreciated I've been at this all evening! :)

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  • Starting with NHibernate

    - by George
    I'm having major difficulties to start off with NHiberante. Main problems: Where my hbm.xml files should reside? I create a Mappings folder but I received an error "Could not find xxx.hbm.xml file." I tried to load the specific class through the dialect cf.AddClass(typeof(xxx)); but it still gives me the same error (the files are marked as embebed resources. Also I'm having major problems in connection to it. I stopped trying to use the cfg xml file and tried a more direct approach with a library I have here. Configuration cfg = new Configuration(); cfg.AddClass(typeof(Tag)); ISessionFactory sessions = cfg.BuildSessionFactory(); AgnosticConnectionHandler agch = new AgnosticConnectionHandler("xxx","xxx","geo_biblio","localhost", 5432,DatabaseInstance.PostgreSQL); ISession sessao = sessions.OpenSession(agch.GetConnection); ITransaction tx = sessao.BeginTransaction(); Tag tag1 = new Tag(); tag1.NomeTag = "Teste Tag NHibernate!!!"; sessao.Save(tag1); tx.Commit(); sessao.Close(); Any tips for me? I'm getting the exception in line 2 of this code, and still not sure what to do. Any help is appreciated. Thanks

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  • Java Random Slowdowns on Mac OS cont'd

    - by javajustice
    I asked this question a few weeks ago, but I'm still having the problem and I have some new hints. The original question is here: http://stackoverflow.com/questions/1651887/java-random-slowdowns-on-mac-os Basically, I have a java application that splits a job into independent pieces and runs them in separate threads. The threads have no synchronization or shared memory items. The only resources they do share are data files on the hard disk, with each thread having an open file channel. Most of the time it runs very fast, but occasionally it will run very slow for no apparent reason. If I attach a CPU profiler to it, then it will start running quickly again. If I take a CPU snapshot, it says its spending most of its time in "self time" in a function that doesn't do anything except check a few (unshared unsynchronized) booleans. I don't know how this could be accurate because 1, it makes no sense, and 2, attaching the profiler seems to knock the threads out of whatever mode they're in and fix the problem. Also, regardless of whether it runs fast or slow, it always finishes and gives the same output, and it never dips in total cpu usage (in this case ~1500%), implying that the threads aren't getting blocked. I have tried different garbage collectors, different sizings the parts of the memory space, writing data output to non-raid drives, and putting all data output in threads separate the main worker threads. Does anyone have any idea what kind of problem this could be? Could it be the operating system (OS X 10.6.2) ? I have not been able to duplicate it on a windows machine, but I don't have one with a similar hardware configuration.

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  • Are document-oriented databases any more suitable than relational ones for persisting objects?

    - by Owen Fraser-Green
    In terms of database usage, the last decade was the age of the ORM with hundreds competing to persist our object graphs in plain old-fashioned RMDBS. Now we seem to be witnessing the coming of age of document-oriented databases. These databases are highly optimized for schema-free documents but are also very attractive for their ability to scale out and query a cluster in parallel. Document-oriented databases also hold a couple of advantages over RDBMS's for persisting data models in object-oriented designs. As the tables are schema-free, one can store objects belonging to different classes in an inheritance hierarchy side-by-side. Also, as the domain model changes, so long as the code can cope with getting back objects from an old version of the domain classes, one can avoid having to migrate the whole database at every change. On the other hand, the performance benefits of document-oriented databases mainly appear to come about when storing deeper documents. In object-oriented terms, classes which are composed of other classes, for example, a blog post and its comments. In most of the examples of this I can come up with though, such as the blog one, the gain in read access would appear to be offset by the penalty in having to write the whole blog post "document" every time a new comment is added. It looks to me as though document-oriented databases can bring significant benefits to object-oriented systems if one takes extreme care to organize the objects in deep graphs optimized for the way the data will be read and written but this means knowing the use cases up front. In the real world, we often don't know until we actually have a live implementation we can profile. So is the case of relational vs. document-oriented databases one of swings and roundabouts? I'm interested in people's opinions and advice, in particular if anyone has built any significant applications on a document-oriented database.

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  • Use of Syntactic Sugar / Built in Functionality

    - by Kyle Rozendo
    I was busy looking deeper into things like multi-threading and deadlocking etc. The book is aimed at both pseudo-code and C code and I was busy looking at implementations for things such as Mutex locks and Monitors. This brought to mind the following; in C# and in fact .NET we have a lot of syntactic sugar for doing things. For instance (.NET 3.5): lock(obj) { body } Is identical to: var temp = obj; Monitor.Enter(temp); try { body } finally { Monitor.Exit(temp); } There are other examples of course, such as the using() {} construct etc. My question is when is it more applicable to "go it alone" and literally code things oneself than to use the "syntactic sugar" in the language? Should one ever use their own ways rather than those of people who are more experienced in the language you're coding in? I recall having to not use a Process object in a using block to help with some multi-threaded issues and infinite looping before. I still feel dirty for not having the using construct in there. Thanks, Kyle

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  • Falling Sand simulation

    - by Erik Forbes
    I'm trying to re-create a 'falling sand' simulation, similar to those various web toys that are out there doing the same thing - and I'm failing pretty hard. I'm not really sure where to begin. I'm trying to use cellular automata to model the behavior of the sand particles, but I'm having trouble figuring out how to make the direction in which I update the 'world' not matter... For example, one of the particle types I'd like to have is Plant. When Plant comes in contact with Water, Plant turns that Water particle into another Plant particle. The problem here though is that if I'm updating the game world from top to bottom and left to right, then a Plant particle placed in the middle of a sea of Water particles will immediately cause all of the Water particles to the right and below that new Plant particle to turn into Plants. This is not the behavior I am expecting. =( I'm having difficulty explaining exactly my difficulty, so I'll try to add more information as best I can as I go along. Suffice it to say that this is very much outside my box, as it were, and I don't even know what to search for.

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  • php fopen function dies, though I have file permissions set to read and write

    - by Matthew Robert Keable
    I'm following a tutorial on php, and am having difficulty getting this to work. I set the appropriate directory permissions to read and write, but every time I run this, I get the die string. The code is: $ourFileName = "testFile.txt"; $ourFileHandle = fopen($ourFileName, 'w') or die("can't open file"); fclose($ourFileHandle); As far as my basic understanding goes, if "testFile.txt" does not exist, fopen should create that file (I have basic knowledge of Python, and remember this same principle in that language). But it...it doesn't. Even if I create the aforementioned file, and put it up, that line of code still returns a die string. My hosting account does not give me permission to execute. Is this a problem? My server runs on Windows. I am using Dreamweaver CS5, on OSX 10.5.8. I've done some searching on this, and see other people having similar issues - but none of them keyed to exactly my range of problems. Being that I'm a beginner, I feel that it might be something I'm overlooking. Thanks!!

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  • Looking for a fast, compact, streamable, multi-language, strongly typed serialization format

    - by sanity
    I'm currently using JSON (compressed via gzip) in my Java project, in which I need to store a large number of objects (hundreds of millions) on disk. I have one JSON object per line, and disallow linebreaks within the JSON object. This way I can stream the data off disk line-by-line without having to read the entire file at once. It turns out that parsing the JSON code (using http://www.json.org/java/) is a bigger overhead than either pulling the raw data off disk, or decompressing it (which I do on the fly). Ideally what I'd like is a strongly-typed serialization format, where I can specify "this object field is a list of strings" (for example), and because the system knows what to expect, it can deserialize it quickly. I can also specify the format just by giving someone else its "type". It would also need to be cross-platform. I use Java, but work with people using PHP, Python, and other languages. So, to recap, it should be: Strongly typed Streamable (ie. read a file bit by bit without having to load it all into RAM at once) Cross platform (including Java and PHP) Fast Free (as in speech) Any pointers?

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  • Multiple on-screen view controllers in iPhone apps

    - by Felixyz
    I'm creating a lot of custom views and controllers in a lot of my apps and so far I've mostly set them up programmatically, with adjustments and instantiations being controlled from plists. However, now I'm transitioning to using Interface Builder as much as possible (wish I had done that before, was always on my back-list). Apple is recommending against having many view controllers being simultaneously active in iPhone apps, with a couple of well-known exceptions. I've never fully understood why it should be bad to have different parts of the interface belong to different controllers, if they have no interdependent functionality at all. Does having multiple controllers risk messing up the responder chain, or is there some other reason that it's not recommended, except for the fact that it's usually not needed? What I want to be able to do is design reusable views and controls in IB, but since a nib is not associated with a view, but with a view controller, it seems I'd have to have different parts of the screen be connected to different controllers. I know it's possible to have other objects than view controllers being instantiated from nibs. Should I look into how to create my own alternative more light-weight controllers (that could be sub-controllers of a UIViewController) which could be instantiated from nibs?

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